There are a number of non J Body cars that I like (not at much as the J bodies, mind you). Magnum GTs and XEs, post 1974 Chargers and first generation Cordobas, 1979 300s, 1975-on Fury 2 doors. Daytona Turbos, 1973-1974 Satellites (Satellites, not Road Runners or GTXs). Late 1960s Mercury Marauders and 1970-1971 Cyclones, 1973-1975 Monte Carlos, 1974-1975 Laguna S3s, mid 1970s Imperials, 1970s 2 door Matadors.. Collector car world has very little regard for any of them. Good; great, even. Keeps prices low so that I can afford them.
As for why people are like this, I can't say with any certainty. I do think its a combination of we're not part of the "in crowd" and thereby don't imply that they have a great car, because we chose something different. THe other part may (just speaking my mind here, no evidence to support this), but the collector car market has become very much the equivalent of the "big gold chain" of the disco era. The "in" collector cars are owned by many people who don't work on their cars. I'm not saying that they can't, but that they don't. They send the car out to a shop to be restored or "built". They get Galen Govier to rubber stamp the history of the car, and they walk around feeling all proud that they are now "cool", "a person of taste", "the man" etc. Like the gold chain I mentioned above, its an ego driven thing. The "in" cars are also assets, they are no longer cars, not driven because the loss in value due to wear and potential accidents makes it financial suicide to drive those >$1.5M 1970 Hemi Cuda Convertibles around. Hey "It's one of 6". Guess what? I don't care. My cars make me happy. They will never be worth $1.5M, maybe they will never become an "in " car. Fine, doesn't change the enjoyment I get out of may cars.
I have neither the money or the inclination to play those games, nor do I want to be in a position to own a car that is so valuable that I wouldn't be able to drive it. A car that isn't driven is not a car, its a statue. And, no I don't agree with its "a work of art". Everything of significant value has become a "work of art" all of a sudden. They aren't.